A device such as an organic light-emitting element, a TFT substrate, or the like makes use of a functional layer that serves a particular function. Examples of functional layers include an organic light-emitting layer in an organic light-emitting element, an organic semiconductor layer in a TFT substrate, and so on.
Presently, device size is increasing. Methods of forming functional layers with good efficacy include a proposed wet process in which an inkjet method is used to apply a solution (hereinafter also termed ink) that contains an organic material. Such a wet process has merits in that the positional precision obtained when forming the functional layer is not dependent on substrate size, and that there are comparatively few technical obstacles to application to larger devices. A wet process using a representative inkjet method involves, firstly, arranging a discharge target on a work table of a solution discharge device and, secondly, discharging the ink solution from a plurality of discharge outlets in an inkjet head as the inkjet head scans a surface of the discharge target. The ink is then deposited on the surface of the discharge target. Subsequently, the deposited ink dries to form the functional layer (see Patent Literature 1).
In the wet process using the inkjet method, the landing accuracy of the solution discharge device must meet a certain standard in order to form the functional layer with high positional precision. That is, the solution discharge device must function to cause a predictable volume of solution to be deposited at a predictable position. In order to check that this functionality is provided, a landing accuracy inspection process is typically performed by causing the solution discharge device to discharge prior to beginning the wet process with the ink jet method.
The landing accuracy inspection process involves discharging the solution from the discharge outlets toward an inspection area provided on an inspection substrate or on a peripheral region of a semi-finished device, imaging the inspection area, and detecting a displacement value and volume for each drop according to a respective image of the drop obtained by imaging. Specifically, for example, the inspection area on which the solution has been deposited is imaged by an imaging device such as a CCD camera, pattern matching or the like is applied to deposits with in the image obtained by imaging to distinguish a main drop, the position of the main drop as distinguished is read, and calculations are performed of the displacement value of the main drop from and of the drop volume from the deposit surface area.